Derivative of tetrahydrobenzothiazole and herbicidal composition containing the same as active ingredient

ABSTRACT

Disclosed herein are the derivatives of tetrahydrobenzothiazole represented by the general formula (I): ##STR1## wherein R 1  represents a hydrogen atom, a straight-chain alkyl group having 1 to 6 carbon atoms or branched-chain alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or a phenyl group and R 2  represents a chemical group selected from the group consisting of: ##STR2## wherein R 3  represents a hydrogen atom, a methyl group or an acetyl group and R 4  represents a hydrogen atom, a hydroxyl group, methoxy group or acetoxy group and herbicidal compositions containing at least one of the derivatives of tetrahydrobenzothiazole as an active ingredient.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to novel derivatives oftetrahydrobenzothiazole represented by the general formula (I): ##STR3##wherein R¹ represents a hydrogen atom, a straight-chain alkyl grouphaving 1 to 6 carbon atoms or branched-chain alkyl group having 1 to 6carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or a phenylgroup and R² represents a chemical group selected from the groupconsisting of: ##STR4## wherein R³ represents a hydrogen atom, a methylgroup or an acetyl group and R⁴ represents a hydrogen atom, a hydroxylgroup, methoxy group or acetoxy group and the herbicidal compositionscontaining at least one of the derivatives of tetrahydrobenzothiazole asan active ingredient.

The present inventors have studied for finding a compound showing anexcellent activity in selectively controlling weeds such as Echinochloacrus-galli, Poa annua, Stetulaca oleracea, Cardamine flexuosa, Portulacaorelacea, etc. without any phytotoxicity to crop plants such as rice,wheat, soybean and maize, and as a result, they have found that aderivative of 1,2,4-triazole, represented by the general formula (I)shows an excellent herbicidal activity for practically controlling theweeds, and have been attained to the present invention.

Each member of the derivatives of tetrahydrobenzothiazole according tothe present invention (hereinafter referred to as the present compound),represented by the general formula (I) exhibited an excellent herbicidalactivity when applied onto foliage of graminaceous weeds andbroad-leaved weeds in herbicidal tests and accordingly, the field ofapplication of the present compound covers the arable lands such aspaddy fields, ordinary crop fields, orchards, etc. and also thenon-arable lands.

The present compounds are generally synthesized from each of thefollowing compounds represented by the general formulae (II) and (III):##STR5## wherein R¹ represents the same as in the general formula (I).

The starting compound represented by the general formula (II) isobtained by reacting methyl isocyanate to the amino compound representedby the general formula (IV): ##STR6## wherein R¹ represents the same asin the general formula (I), and the other starting compound representedby the general formula (III) is obtained by reacting phenylchloroformate with the amino compound represented by the general formula(IV), thereby obtaining a compound represented by the general formula:##STR7## wherein R¹ represents the same as in the general formula (I),and reacting the thus obtained phenyl ester withN-2,2-dimethoxyethyl-N-methylamine.

In the cases where the compound represented by the general formula (II)is used as the starting compound, it is brought into reaction withglyoxal, glyoxalic acid or oxalyl chloride to obtain the presentcompound represented by the general formula (V), (VI) or (VII) shownbelow. ##STR8## (for instance, Compound No. 1, 5, 13, 20, 23 or 26),wherein R¹ represents the same as in the general formula (I). ##STR9##(for instance, Compound No. 17), wherein R¹ represents the same as inthe general formula (I) or ##STR10## (for instance, Compound No. 9, 18,21, 24 or 27), wherein R¹ represents the same as in the general formula(I).

The present compound represented by the general formula (V) can be usedfor synthesizing other members of the present compounds as follows.

Namely, in the case where methanol is brought into reaction with thecompound represented by the general formula (V) and synthesized, thepresent compound represented by the general formula (VIII): ##STR11##wherein R¹ represents the same as in the general formula (I), forinstance, Compound No. 6 or 14, is obtained, and further, by acetylatingthe thus obtained monomethyl ether (VIII), the other present compoundrepresented by the general formula (IX): ##STR12## wherein R¹ representsthe same as in the general formula (I), for instance, Compound No. 2, 7or 15, is obtained.

In addition, by directly acetylating the compound represented by thegeneral formula (V), still another present compound represented by thegeneral formula (X): ##STR13## wherein R¹ represents the same as in thegeneral formula (I), for instance, Compound No. 8 or 16 is obtained.

In the case where the compound represented by the general formula (III)is used as the starting compound, it is brought into reaction with adilute mineral acid to obtain the present compound represented by thegeneral formula (XI): ##STR14## wherein R¹ represents the same as in thegeneral formula (I), for instance, Compound No. 3, 10, 19, 22 or 25, andfurther by acetylation of the thus obtained compound (XI) with acetylchloride, the present compound represented by the general formula (XII):##STR15## wherein R¹ represents the same as in the general formula (I),for instance, Compound No. 4 or 12, is obtained, and instead ofacetylation, by treating the compound represented by the general formula(XI) with methanol in the presence of a catalytic amount of H₂ SO₄, thepresent compound represented by the general formula (XIII): ##STR16##wherein R¹ represents the same as in the general formula (I), forinstance, Compound No. 11 is obtained.

The concrete examples of the present compounds are shown in Table 1 withthe melting point and the process of synthesis thereof, simplifiedstructural formula being given to the heterocyclic group thereof.

                  TABLE 1                                                         ______________________________________                                        No. of                                                                        present                      Melting point                                    com-  Substituent            (°C.) and color                           pound R.sup.1   R.sup.2          Appearance                                   ______________________________________                                        1     H                                                                                        ##STR17##       210 (decomp.) white crystal                  2     H                                                                                        ##STR18##       122-124 white crystal                        3     CH.sub.3                                                                                 ##STR19##       217-218 (decomp.) white crystal              4     CH.sub.3                                                                                 ##STR20##       171-174 white crystal                        5     CH.sub.3                                                                                 ##STR21##       195-197 (decomp.) white crystal              6     CH.sub.3                                                                                 ##STR22##       162-163 white crystal                        7     CH.sub.3                                                                                 ##STR23##       168-170 white crystal                        8     CH.sub.3                                                                                 ##STR24##       173-175 white crystal                        9     CH.sub.3                                                                                 ##STR25##       198-200 white crystal                        10                                                                                   ##STR26##                                                                               ##STR27##       185-187 white crystal                        11                                                                                   ##STR28##                                                                               ##STR29##       149-150 white crystal                        12                                                                                   ##STR30##                                                                               ##STR31##       154-157 white crystal                        13                                                                                   ##STR32##                                                                               ##STR33##       172-175 white crystal                        14                                                                                   ##STR34##                                                                               ##STR35##       138-140 pale yellow crystal                  15                                                                                   ##STR36##                                                                               ##STR37##       125-128 white crystal                        16                                                                                   ##STR38##                                                                               ##STR39##       122-124 white crystal                        17                                                                                   ##STR40##                                                                               ##STR41##       210-211 white crystal                        18                                                                                   ##STR42##                                                                               ##STR43##       188-189 pale yellow crystal                  19                                                                                   ##STR44##                                                                               ##STR45##       168-170 white crystal                        20                                                                                   ##STR46##                                                                               ##STR47##       188-190 (decomp.) white crystal              21                                                                                   ##STR48##                                                                               ##STR49##       190-191 white crystal                        22    Phenyl                                                                                   ##STR50##       230-231 white crystal                        23    Phenyl                                                                                   ##STR51##       210 (decomp.) white crystal                  24    Phenyl                                                                                   ##STR52##       208-212 white crystal                        25    Cyclohexyl                                                                               ##STR53##       194-197 white crystal                        26    Cyclohexyl                                                                               ##STR54##       164-168 (decomp.) white crystal              27    Cyclohexyl                                                                               ##STR55##       175-177  yellowish crystal                   ______________________________________                                         Note:                                                                         AcO of Compound Nos. 2, 4, 7, 8, 12, 15, 16 mean Acetoxy group           

Of the attached drawings, FIGS. 1 to 27 show the infrared absorptionspectrum of Compounds Nos. 1 to 27 according to the present invention,respectively.

The following are the synthetic examples of some of the presentcompounds, the number of each compound corresponding to that shown inTable 1.

Concrete examples of the synthetic process for obtaining the presentcompound are shown as follows.

SYNTHETIC EXAMPLE 1 Synthesis of1-(5-t-butyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-4,5-dihydroxy-3-methyl-1,3-imidazolidin-2-one(CompoundNo. 20)

Into a solution of 2.0 g(0.0071 mol) ofN-(5-t-butyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-N'-methylurea(Compoundrepresented by the general formula (II) wherein R¹ is a t-butyl group)in 50 ml of ethanol, an aqueous 40% solution containing 2.6 g of glyoxalwas added, and the mixture was heated under a reflux condenser for 2hours.

After distilling the solvent from the reaction mixture, the residue wasextracted with chloroform, and the extract was washed with water anddried. After distilling chloroform from the dried extract, the residualoily material was solidified with the addition of hexane, and the solidmaterial was washed with ethyl acetate to obtain 2.35 g of crystalsmelting at 188° to 190° C. with decomposition, in a yield of 98%. IRabsorption spectrum and NMR spectrum thereof gave the following data:

IR absorption band (as KBr tablet, cm³¹ 1): ν_(OH) 3250, ν_(CO) 1710 and1620.

MNR spectrum (DMSO-d₆, ppm)δ: 0.93 (9H, s: H of t-butyl group at5-position), 1.8 to 3.0(5H, m: H of 4-(two), 5-(one) and 6-(two)positions), 2.87(3H, s: H of methyl group at 3'-position), 4.75(1H, d,J=8 Hz: H at 4'-position), 5.47(1H, d, J=8 Hz: H at 5'-position), 6.62(1H, d, J=8 Hz: H of OH at 4'-position) and 7.08(1H, d, J=8 Hz: H of OHat 5'-position).

SYNTHETIC EXAMPLE 2 Synthesis of5-hydroxy-4-methoxy-3-methyl-1-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-1,3-imidazolidin-2-one(CompoundNo. 6)

Into a solution of 3.0 g(0.01 mol) of4,5-dihydroxy-1-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2benzothiazolyl)-2-imidazolidinone(CompoundNo. 1) synthesized fromN-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-N'-methylurea bythe similar procedures to those in Synthetic Example 1 in 30 ml ofmethanol, 3 drops of conc.H₂ SO₄ was added, and the mixture was heatedfor 1 hour under a reflux condenser. After washing the solid materialobtained by distilling methanol from the reaction mixture, with water,the solid material was recrystallized from methanol and further from amixture of chlorofrom and hexane to obtain 1.65 g of crystals melting at162° to 163° C. in a yield of 53%. IR spectral data and NMR spectraldata thereof are shown below:

IR absorption band(as KBr-tablet: cm³¹ 1): ν_(CO) 1720 and 1640.

NMR spectrum(DMSO-d₆ :ppm): δ1.12(3H, broad s: H of methyl group at5-position), 2.15 to 2.75(5H, m: H of 4-(two), 5-(one) and 6-(two)positions), 3.01(3H, s: H of methyl group at 3'-position), 3.42(3H, s: Hof methoxy group at 4'-position), 4.75(1H, s: H at 4'-position),5.07(1H, broad s: H of OH at 5'-position) and 5.80(1H, s: H of5'-position).

SYNTHETIC EXAMPLE 3 Synthesis of5-acetoxy-1-(5-isopropyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-3-methyl-4-methoxy-1,3-imidazolidin-2-one(CompoundNo. 15)

After heating a solution of 5 g(0.015 mol) of1-(5-isopropyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-3-methyl-4,5-dihydroxy-1,3-imidazolidin-2-one(CompoundNo. 13) obtained by the similar procedures to those in Synthetic Example1 in 200 ml of anhydrous methanol in the presence of a catalytic amountof con. H₂ SO₄ under a reflux condenser, methanol was distilled off thereaction mixture, and the residue was extracted with chloroform. Afterwashing the extract with water, the washed extract was subjected tosilica-gel column-chromatography to obtain 3 g of purified crystalswhite in color melting at 138° to 140° C., the thus obtained crystalhaving been identified to be Compound No. 14 represented by the generalformula (I) wherein R¹ is an isopropyl group; R³ is a hydrogen atom andR⁴ is a methoxy group by IR absorption bands thereof at 3400, 1730, 1632and 1365 cm⁻¹.

Into an ice-cooled solution of 3 g(0.009 mol) of the thus obtainedcrystals of Compound No. 14 in 50 ml of pyridine, 0.83 g(0.01 mol) ofacetyl chloride was added drop by drop followed by stirring for 10 min.Then, after stirring the reaction mixture for 2 hours at a roomtemperature, pyridine was distilled off from the mixture and the residuewas extracted with chloroform. After washing the extract with water, thewashed extract was subjected to silica-gel column chromatography toobtain 0.4 g of purified white crystals melting at 125° to 128° C. Thethus obtained crystalline product was identified as the object compoundNo. 15 by analysis of NMR spectrum thereof as follows:

NMR Spectrum(CDCl₃, ppm)δ:0.1(6H, d, J=6 Hz: H of two methyl groups ofisopropyl group at 5-position), 1.46 to 2.91 (6H, m: H of 4-(two),5-(one) and 6-(two) positions and H of isopropyl group, other than thoseof two methyl groups, at 5-position), 2.17(3H, s: H of COCH₃ at5'-position), 3.04(3H, s: H of methyl group to N at 3'-position),3.58(3H, s: H of methoxy group at 4'-position), 4.71(1H, s: H at4'-position) and 6.81(1H, s: H at 5-position).

SYNTHETIC EXAMPLE 5 Synthesis of4-hydroxy-1-(5-isopropyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-3-methyl-1,3-imidazolidin-2,5-dione(CompoundNo. 17)

A mixture of 2.7 g(0.01 mol) ofN-methyl-N'-(5-isopropyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)urea(Compoundrepresented by the general formula(II) wherein R¹ is an isopropylgroup), 1.2 g(0.013 mol) of glyoxalic acid monohydrate and 25 ml ofbenzene was heated for 2 hours under a reflux condenser while removingthe azeotropically distilled water. After cooling the reaction mixture,the separated crystals were collected by filtration, washed with waterand recrystallized from a mixture of benzene and ethanol to obtain 1.6 gof crystals melting at 210° to 211° C., in a yield of 47%. IR absorptionbands and NMR spectrum thereof are shown below:

IR absorption bands(as KBr tablet, cm⁻¹): ν_(OH) 3320, ν_(CO) 1800, 1740and 1660.

NMR spectrum(DMSO-d₆, ppm): δ0.92(6H, d, J=6 Hz:H of methyl group ofisopropyl group at 5-position), 1.48 to 3.41 (6H, m: H of 4-, 5- and6-positions and H of CH of isopropyl group at 5-position), 2.90(3H, s: Hof methyl group at 1'-position), 5.18(1H, d, J=9 Hz:H at 5'-position),and 7.18(1H, d, J=9 Hz: H of OH at 5'-position).

SYNTHETIC EXAMPLE 6 Synthesis of5-acetoxy-4-methoxy-3-methyl-1-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-1,3-imidazolidin-2-one(CompoundNo. 7)

After adding 1.1 g(0.0035 mol) of Compound No. 6 synthesized inSynthetic Example 2 to a mixture of 10 ml of acetic anhydride and 0.95 gof sodium acetate, the mixture was heated for 1.5 hours under a refluxcondenser. Then, the reaction mixture was poured into iced water and thethus separated crystals were collected by filtration, washed with waterand then recrystallized from ethanol to obtain 0.96 g of a crystallineproduct melting at 168° to 170° C. in a yield of 80%.

IR spectral data and NMR spectral data of the thus obtained compound areshown below:

IR absorption band(as KBr tablet, cm⁻¹): ν_(CO) 1730 and 1650. NMRspectrum(DMSO-d₆, ppm)δ1.21 (3H, broad d, J=4 Hz: H of methyl group at5-position), 1.93(1H, m: H at 5position), 2.10(3H, s: H of OCOCH₃ at5'-position), 2.30 to 2.70 (4H, m: H of 4- and 6- positions), 3.01(3H,s: H of methyl group at 3'-position), 3.55(3H, s: H of methoxy group at4'-position), 4.63(1H, s: H at 4'-position) and 6.73(1H, s: H at5'-position).

SYNTHETIC EXAMPLE 7 Synthesis of4,5-diacetoxy-3-methyl-1-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-1,3-imidazolidin-2-one(CompoundNo. 8)

To 20 ml of acetic anhydride, 2.0 g(0.0067 mol) of4,5-dihydroxy-3-methyl-1-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-1,3-imidazolidin-2-one(CompoundNo. 5) produced by the similar procedures to those in Synthetic Example1 and 3 drops of conc. H₂ SO₄ were added, and the mixture was stirredfor 30 min at 60° C. Then, the reaction mixture was poured into icedwater, and the thus separated crystals were collected by filtration andrecrystallized from methanol to obtain 1.5 g of white crystals meltingat 173° to 175° C., in a yield of 66%. IR spectral data and NMR spectraldata thereof are shown below:

IR absorption bands(as KBr-tablet, cm⁻¹): ν_(CO) 1730 and 1650.

NMR spectrum(CDCl₃, ppm): δ1.20(1H, broad d, J=4 Hz: H of methyl groupat 5-position), 2.15(6H, s: H of two acetoxy groups at 4'-and5'-positions), 2.30 to 2.85 (5H, m: 4-(two), 5-(one) and 6-(two)positions), 3.02(3H, s: H of methyl group at 3'-position), 6.06(1H, s: Hat 4'-position) and 6.85(1H, s: H at 5'-position).

SYNTHETIC EXAMPLE 8 Synthesis of5-hydroxy-3-methyl-1-(5methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-1,3-imidazolidin-2-one(CompoundNo. 3) (8-1) Preparation of the starting compound represented by thegeneral formula(III)

Into a suspension of 8.7 g(0.03 mol) of phenyl5-methyl-4,5,6,7-tetrahydro-7-oxo-2benzothiazolylcarbamate(Compoundrepresented by the general formula(IV) wherein R¹ is a methyl group) in50 ml of DMF, 5.1 g(0.04 mol) of N-2,2-dimethoxyethyl-N-methylamine wasadded, and the mixture was stirred for 3 hours under a reflux condenser.After distilling DMF from the reaction mixture, the residue wasdissolved in chloroform, and the solution was washed with an aqueous 10%solution of sodium carbonate and then with water. By distillingchloroform from the washed solution, pale yellow crystals melting at226° C. with decomposition were obtained in an amount of 5.6 g.

The thus obtained crystalline substance was identified as the compoundrepresented by the general formula(III) wherein R¹ is a methyl groupaccording to IR absorption bands (as KBr-tablet) of 3410, 3160, 1750 and1660 cm⁻¹ thereof.

(8-2) Synthesis of Compound No. 3

A solution of 5.6 g(0.017 mol) of the thus obtained starting compound ina mixture of 35 ml of ethanol and 47 ml of an aqueous 8.8% solution ofhydrogen chloride was heated for 30 min under a reflux condenser andthen cooled to a room temperature. The thus separated crystals werecollected by filtration, washed with water and again washed with warmacetone to obtain 1.8 g of white crystals melting at 217° to 218° C.with decomposition. The thus obtained crystalline substance wasidentified as Compound No. 3 according to the NMR spectral data thereofas follows:

NMR spectrum(d-DMSO, ppm) δ: 1.13(3H, broad d: H of methyl group at5-position), 1.5 to 2.73(5H, m: H of 4(two)-, 5(one)- and6(two)-positions), 2.87(3H, s: H of methyl group at 3'-position),3.32(1H, dd, J=3 Hz, 11 Hz: H at 4'-position), 5.85 to 6.18(1H, m: H ofOH at 5'-position) and 7.12(1H, dd, J=3 Hz : 7 Hz: H at 5'-position).

SYNTHETIC EXAMPLE 9 Synthesis of5-acetoxy-3-methyl-1-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-1,3-imidazolidin-2-one(CompoundNo. 4)

Into an ice-cooled solution of 2 g(0.007 mol) of5-hydroxy-3-methyl-1-(5-methyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazol-2-yl)-1,3-imidazolidin-2-one(CompoundNo. 3) synthesized in Synthetic Example 8 in 40 ml of pyridine, 0.67g(0.008 mol) of acetyl chloride was added drop by drop, and the mixturewas stirred for 10 min. After additionally stirring the mixture for 2hours at a room temperature, pyridine was distilled from the mixture andthe residue was collected by filtration, washed with water and thenrecrystallized from ethanol to obtain 1.0 g of white crystals melting at171° to 174° C. The identification of the thus obtained crystallinesubstance was carried out according to the NMR spectral data as followsresulting in Compound No. 4:

NMR spectrum(CDCl₃, ppm) δ: 1.13(3H, broad d: H of methyl group at5-position), 1.68 to 2.85(5H, m: Hat 4-, 5- and 6-positions), 2.1 (3H,s: H of acetyl group at 5'-position), 2.99(3H, s: N--CH₃ at3'-position), 3.44(1H, dd, J=3 Hz, 11 Hz: H at 4'-position), 3.92(1H,dd, J=7 Hz, 11 Hz: Hat 4'-position) and 6.96(1H, dd, J=3 Hz, 7 Hz: Hat5'-position).

SYNTHETIC EXAMPLE 10 Synthesis of5-hydroxy-3-methyl-1-(5-phenyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-1,3-imidazolidin-2-one(CompoundNo. 22) (10-1) Preparation of the starting compound represented by thegeneral formula(III) wherein R¹ is a phenyl group

To a mixture of 3.6 g(0.01 mol) of phenyl5-phenyl-4,5,6,7-tetrahydro-7-oxo-benzothiazole-2-ylcarbamate and 1.2 g(0.011 mol) of N-2,2-dimethoxyethyl-N-methylamine, 15 ml of DMF wasadded, and after heating the whole system for 3 hours at 70° to 80° C.,the reaction mixture was condensed, and the product was transferred intobenzene. After washing the benzene solution with an aqueous 10% solutionof sodium carbonate and drying the washed solution on anhydrous sodiumsulfate, benzene was distilled off from the dried solution to obtin thestarting compound in crude state.

(10-2) Synthesis of Compound No. 22

The whole amount of the thus obtained starting compound was heated in amixture of 15 ml of ethanol and 70 ml of an aqueous 5% solution of H₂SO₄ for 2 hours at 80° C., and the thus separated crystals werecollected by filtration. After washing the crystals with water, thecrystals were recrystallized from a mixture of 20 ml of acetic acid and10 ml of DMF to obtain 1.45 g of colorless crystals melting at 230° to231° C. in a yield of 42.6%. The thus obtained compound was identifiedto be Compound No. 22 according to the following IR data and NMR data:

IR absorption bands(KBr-tablet, cm⁻¹): ν_(OH) 3300 and ν_(CO) 1720 and1630.

NMR spectrum(DMSO-d₆, ppm): δ2.63 to 3.94(7H, m: H of 4(two)-, 5(one)-,6(two)- and 4'(two)-positions), 2.87(3H, s: H of methyl group at3'-position), 5.98(1H, t: H of OH at 5'-position), 7.02 (1H, q: H at5'-position) and 7.40 (5H, d: H of phenyl group).

SYNTHETIC EXAMPLE 11 Synthesis of1-(5-cyclohexyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazolyl)-3-methyl-1,3-imidazolidin-2,4,5,-trione(Compound No. 27)

Into 80 ml of chloroform(once washed with water and dried on anhydrousCaCl₂), 4 g (0.013 mol) ofN-(5-cyclohexyl-4,5,6,7-tetrahydro-7-oxo-2-benzothiazole-2-yl)-N-methylurea(Compound represented by the general formula(II) wherein R¹ is acyclohexyl group) was added, and while gently stirring the mixture, 1.7ml (0.020 mol) of oxalyl chloride was added at room temperature and thewhole system was heated under mild reflux for 70 min to obtain a uniformmixture. After adding 80 ml of petroleum ether to the uniform mixtureand leaving the mixture to stand still for one hour at a roomtemperature, pale yellow crystals separated from the mixture. Thecrystals were collected by filtration and by adding 80 ml of petroleumether to the filtrate and leaving the mixture to stand still for anight, additional amount of pale yellow crystals separated. The twoportions of the crystals melting at 175°-177° C. when combined weighed3.7 g, which were identified as the object compound according to thefollowing analytical data:

IR absorption bands(KBr tablet, cm⁻¹): 2925, 2850, 1790, 1740, 1660,1460, 1450 and 1360.

NMR spectrum(DMSO-d₆, ppm): δ0.63 to 2.97(16H) and 3.03 (3H, s).

In cases where the present compound represented by the generalformula(I) is used for weed-control, the compound may be applied aloneor after diluting to a suitable concentration with a diluent as in theapplication of a conventional herbicidal compound, the diluted materialmay be applied in a procedure such as spraying and scattering, or it isapplicable after admixing with adjuvant(s) such as spreader, wettingagent, sticker, etc.

In addition, since there are no possibility of the decomposition or thedenaturation of the present compound when it is admixed with otherphysiologically active substances nor possibility of decomposing ordenaturating such physiologically active substances, the presentcompound may be used together with the physiologically activesubstances, for instance, fungicides, bactericides, insecticides,herbicides, plant growth regulators or fertilizers or may be used afteradmixing with them.

The present invention will be explained more in detail on thepreparation of the herbicidal compositions containing the presentcompound as an active ingredient and on the herbicidal activity of thepresent compound while referring to the nonlimitative examples. Inpreparing the herbicidal composition, the kinds of the diluents andadjuvants, the ratio of the present compound to the diluents andadjuvants and the kinds of the present compound in the composition canbe adopted from a wide range.

FORMULATION EXAMPLE 1 Preparation of a wettable powder

The following components were mixed, and the mixture was well pulverizedto obtain a wettable powdery composition. The product, so-called"wettable powder" is used after diluting with water.

50 parts by weight of Compound No. 3

5 parts by weight of a lignisulfonate

3 parts by weight of an alkylsulfonate and

42 parts by weight of diatomaceous earth.

FORMULATION EXAMPLE 2 Preparation of an emulsifiable concentrate

The following components were uniformly mixed together to obtain acomposition, so-called "emulsifiable concentrate".

25 parts by weight of Compound No. 10

65 parts by weight of xylene and

10 parts by weight of polyoxyethylene alkyl aryl ether.

The thus prepared "emulsifiable concentrate" is used after diluting withwater.

FORMULATION EXAMPLE 3 Preparation of a granular composition

The following components were uniformly mixed together, and afterfurther adding water to the mixture and kneading the moistured mixture,the kneaded material was extruded from an extruding granulator to begranules and dried to be so-called "granule". These "granules" aredirectly applied onto foliage or soil.

EXAMPLE 1 (Herbicidal Test)

In a planter of the dimensions of 650×210×200 mm soil taken from a cropfield was packed to be a plot, and after sowing seeds of the test plantonto the packed soil, the planter was put under cares of plant growing.At the predetermined plant growth stage, an aqueous suspension of one ofthe present compounds at a concentration of 0.2% by weight, which wasobtained by diluting a wettable powder prepared in a similar manner sothat in Composition Example 1 with water, was sprayed onto the foliageof the plants in the planter at a rate of 10 liters per are of the soilsurface area. After 20 days of spraying, the state of the thus treatedplants in the planter was observed to find the degree of phytotoxicsymptom on the plants according to the following criteria. The degree ofphytotoxic sympton directly corresponds to the herbicidal activity ofthe herbicide on the plant species. The result of the above-mentionedherbicidal tests is shown in Table 2.

    ______________________________________                                        Criteria of evaluating the herbicidal activity                                Criteria        Degree of phytotoxicity                                       ______________________________________                                        0               no phytotoxic symptoms                                        1               very slight symptoms                                          2               slight symptoms                                               3               moderate symptoms                                             4               severe symptoms                                               5               withered                                                      ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                         Result of Herbicidal Test                                                    Herbicidal activity                                                                  Plant species                                                          No. of   Weed plants.sup.(1)                                                                          Crop plants.sup.(2)                                   compound 1     2     3   4    5   1   2   3    4   5   6                      ______________________________________                                         5       3     3     5   5    5   --  0   0    --  --  0                       6       3     4     5   5    5   --  0   0        --  1                       7       2     3     5   5    5   --  0   0    --  --  0                       8       3     3     5   4    5   --  0   0    --  --  0                       9       3     4     5   5    4   --  0   0        --  0                      14       4     5     5   2    5   --  2   0    --  --  0                      16       2     2     5   3    5   --  0   0    --  --  0                      17       3     3     5   3    3   --  1   0    --  --  0                      18       3     2     5   4    5   --  0   0    --  --  0                      19       2     5     5   5    5   --  2   0    --  --  1                      20       3     4     5   5    5   --  0   0    --  --  0                      21       1     1     5   3    5   --  0   0    --  --  0                      22       3     2     5   5    5   --  0   0    --  --  0                      23       3     2     5   3    3   --  0   0    --  --  0                      24       2     3     5   2    5   --  0   0    --  --  0                      25       2     2     3   2    3   --  0   0    --  --  0                      26       2     3     5   2    4   --  0   0    --  --  0                      27       1     2     5   2    5   --  0   0    --  --  0                      ______________________________________                                        Note: Name of Plant species tested                                            .sup.(1) Weed plants .sup.(2) Crop plants                                     1: Echinocloa crus-galli                                                                           1: Rice                                                  2: Poa annua         2: Wheat                                                 3: Stellaria media   3: Maize                                                 4: Portulaca oleracea                                                                              4: Cucumber                                              5: Cardamine flexuosa                                                                              5: Tomato                                                                     6: Soybean                                           

EXAMPLE 2 (Herbicidal Test)

In a planter of the dimensions of 650×210×200 mm, soil taken from a cropfield was packed to be a plot, and after sowing seeds of the test plantonto the packed soil, the planter was put under cares of plant growing.At the predetermined plant growth stage, an aqueous suspension of one ofthe present compounds at a concentration of 0.2% by weight, which wasobtained by diluting a wettable powder prepared in a similar manner tothat in Composition Example 1 with water, was sprayed onto the foliageof the plants in the planter at a rate of 10 liters per are of the soilsurface area. After 20 days of spraying, the state of the thus treatedplants in the planter was observed to find the degree of phytotoxicsymptom on the plants according to the following criteria. The degree ofphytotoxic symptom directly corresponds to the herbicidal activity ofthe herbicide on the plant species. The result of the above-mentionedherbicidal tests is shown in Table 3.

    ______________________________________                                        Criteria of evaluating the herbicidal activity                                Criteria        Degree of phytotoxicity                                       ______________________________________                                        0               no phytotoxic symptoms                                        1               very slight symptoms                                          2               slight symptoms                                               3               moderate symptoms                                             4               severe symptoms                                               5               withered                                                      ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                         Result of Herbicidal Test                                                    Herbicidal activity                                                                  Plant species                                                          No. of   Weed plants.sup.(1)                                                                          Crop plants.sup.(2)                                   compound 1     2     3   4    5   1   2   3    4   5   6                      ______________________________________                                         1       3     4     5   5    3   1   2   0    5   3   4                       2       4     5     5   3    3   0   1   0    2   3   2                       3       4     4     5   4    5   4   4   4    5   5   5                       4       4     4     5   5    5   4   3   5    5   5   5                      10       5     5     5   5    5   4   5   5    5   5   5                      11       3     5     4   4    5   0   0   0    0   2   2                      12       2     3     5   4    5   4   3   4    4   5   5                      13       3     5     5   3    5   4   3   1    5   5   3                      15       3     4     5   4    5   3   3   5    5   5   4                      ______________________________________                                        Note: Name of Plant species tested                                            .sup.(1) Weed plants .sup.(2) Crop plants                                     1: Echinocloa crus-galli                                                                           1: Rice                                                  2: Poa annua         2: Wheat                                                 3: Stellaria media   3: Maize                                                 4: Portulaca oleracea                                                                              4: Cucumber                                              5: Cardamine flexuosa                                                                              5: Tomato                                                                     6: Soybean                                           

EXAMPLE 3 (Herbicidal Test) Herbicidal tests by foliar application ofthe present compound

To the seedlings of the plants shown below respectively grown from theseeds sown in a field (1 m × 1 m), an aqueous suspension containingrespective 0.5 to 0.1%by weight of each of the present compound preparedby diluting each of the wettable powders (so-called wettablecompositions) prepared as Preparation Example 1 andalkylphenolpolyethylene glycolether as a spreader agent was srayed froma small sprayer at a rate of 10 liters per are of the soil surface tosufficiently wet the foliage of the plants. After 20 days of thetreatment, the plants of the remaining treated plants above ground wereweight (without drying) and the value thereof represented by A g/unitarea was compared with that of the untreated plants represented by Bg/unit area.

The results are shown by A/B (%) in Table 4.

                                      TABLE 4                                     __________________________________________________________________________                 No. of compound                                                               1     2    3    4      10   11   12   13   15                                 Concentration (%)                                                Plant        0.05                                                                              0.1                                                                             0.05                                                                             0.1                                                                             0.05                                                                             0.1                                                                             0.05                                                                              0.1                                                                              0.05                                                                             0.1                                                                             0.05                                                                             0.1                                                                             0.05                                                                             0.1                                                                             0.05                                                                             0.1                                                                             0.05                                                                              0.1               __________________________________________________________________________    Portulaca oleracea                                                                         0    0                                                                              13  0                                                                               0  0                                                                              0    0  0  0                                                                               0  0                                                                               0  0                                                                               0  0                                                                               0   0                Amaranthus lividus                                                                         0    0                                                                               8  0                                                                               0  0                                                                              0    0  0  0                                                                               0  0                                                                               14                                                                               0                                                                               0  0                                                                               0   0                Chenopodium album                                                                          0    0                                                                              24  5                                                                               0  0                                                                              0    0  0  0                                                                              26 13                                                                               11                                                                               0                                                                               0  0                                                                              18   0                Glycine max (Soybean)*                                                                     97  95                                                                              98 98                                                                              95 92                                                                              107  99                                                                              93 76                                                                              88 92                                                                              105                                                                              99                                                                              93 52                                                                              93  102               Glycine max (Soybean)**                                                                    102 96                                                                              97 95                                                                              98 96                                                                              111 102                                                                              88 65                                                                              93 87                                                                               97                                                                              89                                                                              85 48                                                                              108  99               __________________________________________________________________________     Variety                                                                       *(Shirome ch-usei)                                                            **(Toyosuzu)                                                             

What is claimed is:
 1. A derivative of tetrahydrobenzothiazolerepresented by the general formula (I): ##STR56## wherein R¹ representsa hydrogen atom, a straight-chain alkyl group having 1 to 6 carbon atomsor branched-cahin alkyl group having 1 to 6 carbon atoms, a cycloalkylgroup having 3 to 6 carbon atoms or a phenyl group and R² represents achemical group selected from the group consisting of: ##STR57## whereinR³ represents a hydrogen atom, a methyl group or an acetyl group and R⁴represents a hydrogen atom, a hydroxyl group, methoxy group or acetoxygroup.
 2. A derivative of tetrahydrobenzothiazole of claim 1, wherein R¹represents t-butyl group, isopropyl group or phenyl group and R²represents a chemical group selected from the group consisting of:##STR58## wherein R³ represents a hydrogen atom and R⁴ represents ahydrogen atom or a hydroxyl group.